Metal channels are commonly used as components in many types of built assemblies. Currently, one of the primary problems associated with the use of these metal channels as framing members involves their high level of thermal transmission due to conductivity. In these built assemblies, a thermal bridge is created by the metal channels through which heat may be transferred. The transfer of heat across this thermal bridge, in turn, manifests itself in the form of increased energy consumption. A number of attempts to solve this problem have been proposed; however, all of these prior proposals present significant disadvantages that severely limit and in some cases eliminate their practical application and use.
For example, U.S. Pat. No. 5,235,054 to Gilmour describes a thermal metallic building stud which attempts to limit contact between the metal framing member and adjacent materials via an upset pattern of punched protuberances which are pushed from the interior surfaces outwardly and cover the length and width of the stud flange. These punched projections present two significant problems: one involving the common use of mechanical fastening devices in conjunction with metal framing and one regarding the industry standardized structural widths currently used for metal framing members. Firstly, the distribution of projections across the width of the flange and away from the web serves as an obstruction to commonly used fasteners such as screws or nails. When hit, these protrusions can cause those fasteners to deflect and bend. This is illustrated in FIGS. 4 and 5 of the Gilmore patent. Secondly, unless the total structural depth of the stud is reduced accordingly, whereby its load bearing capacity is altered, the increased dimension resulting from the outwardly struck protuberances will hinder the use of the described thermal metallic building stud within standardized systems of metal runners and aim channels.
Another example is U.S. Pat. No. 5,592,796 to Landers, which describes how to limit contact between the metal framing member and adjacent materials via a inwardly bent flange, resulting in two contact points between the framing member and the adjacent materials, which extend for the length of the framing member. These two points create an air pocket between the framing member and the adjacent materials. While this air pocket does reduce the amount of thermal transfer between the framing member and the adjacent materials, the thermal transfer could be further reduced. Also, the air pocket creates problems with the use of fasteners which secure the framing member to the adjacent materials. First, when a fastener is inserted through the adjacent materials, it is free to move within the air pocket and may not squarely contact the flange of the framing material. Second, the air pocket provides no support for the adjacent materials. As the fastener is secured, it can be secured so tightly as to deform or break the adjacent materials.
Another problem with traditional structural framing members is that they act as a bridge to transmit acoustic vibrations. When assembled into a built assembly, traditional structural framing members transmit sounds from one side of the built assembly to the other side of the built assembly. For example, when the built assembly is a wall, sounds are transmitted from one side of the wall to the other. This acoustic transmission can be disadvantageous, especially in applications such as apartment buildings, hotels, sound-sensitive laboratories, and the like.
As a result, a need currently exists for thermally-improved metallic channels which possess characteristics not exhibited by the prior art. A need also exists for a method of designing a construction assembly which possess characteristics not exhibited by the prior art.